Watt Hours to Amp Hours Calculator
Convert battery capacity units instantly for solar, RV, and energy storage systems
Enter the energy capacity in watt hours
Battery system voltage (typically 12V, 24V, or 48V)
Calculation Result
Formula Used:
Ah = Wh ÷ V = 1200 ÷ 12 = 100.00 Ah
Battery Capacity Reference
Quick Tip
Higher voltage systems can deliver the same energy with lower amp hours, reducing wire gauge requirements and improving efficiency.
When to Use Wh to Ah Calculator
Solar System Design
Calculate required battery bank capacity for off-grid solar installations. Determine how many amp hours you need based on your daily energy consumption in watt hours and system voltage.
Battery Comparison
Compare batteries from different manufacturers that use different rating units. Convert all specifications to the same unit to make accurate capacity comparisons and informed purchasing decisions.
RV Electrical Planning
Size your RV battery bank correctly by converting your daily power needs from watt hours to amp hours. Ensure your batteries can support your appliances, lights, and electronics while boondocking.
Backup Power Sizing
Calculate battery capacity needed for emergency backup systems. Determine the amp hour rating required to power essential devices during outages based on your watt hour requirements and backup duration.
Marine Applications
Design boat electrical systems with proper battery capacity. Convert between watt hours and amp hours to select batteries that meet your navigation equipment, lighting, and appliance power requirements.
DIY Energy Projects
Build custom battery packs and energy storage solutions with accurate capacity calculations. Convert between units to match your project requirements and ensure proper battery selection for DIY applications.
Understanding Wh to Ah Conversion
The Basic Formula
Ah = Wh ÷ V
Ah = Amp Hours (charge capacity)
Wh = Watt Hours (energy capacity)
V = Volts (system voltage)
Amp hours measure electrical charge capacity over time, while watt hours measure total energy. To convert from energy to charge, you must divide by voltage since watts equals volts times amps.
Example: A 1200Wh battery at 12V has 100Ah capacity (1200 ÷ 12 = 100). The same 1200Wh battery at 24V would only need 50Ah (1200 ÷ 24 = 50).
Common Battery Voltages
Li-ion single cell batteries, power banks, portable devices
Cars, small RVs, boats, portable solar systems, backup power
Large RVs, commercial vehicles, mid-size solar installations
Home solar systems, off-grid houses, large energy storage
Frequently Asked Questions
What is the difference between Watt Hours and Amp Hours?
Watt hours (Wh) measure total energy capacity, while amp hours (Ah) measure electrical charge capacity. Wh considers both voltage and current (Wh = Ah × V), making it a more complete measure of battery energy. Ah only measures current over time and requires knowing the voltage to determine actual energy capacity. Think of Wh as the total work a battery can do, while Ah measures how much electrical charge flows.
How do I convert Watt Hours to Amp Hours?
To convert watt hours to amp hours, divide the watt hours by the battery voltage using the formula: Ah = Wh ÷ V. For example, a 1200Wh battery at 12V equals 100Ah (1200 ÷ 12 = 100). You must know the system voltage to perform this calculation. The voltage is typically marked on your battery or specified in your system documentation.
Is this Wh to Ah calculator free to use?
Yes, this calculator is completely free to use with no registration, downloads, or hidden fees required. You can perform unlimited conversions for battery capacity planning, solar system design, RV electrical systems, and any other applications requiring Wh to Ah calculations. All features are available without any restrictions.
What voltage should I use for my battery system?
Common battery system voltages are 12V (small RVs, boats, portable power, automotive), 24V (larger RVs, commercial vehicles, marine systems), and 48V (solar energy storage, off-grid homes, large installations). The voltage is typically marked on your battery label or in the system specifications. Always use the actual nominal voltage of your system for accurate calculations. Using the wrong voltage will result in incorrect capacity calculations.
Can I use this calculator for solar battery sizing?
Absolutely. This calculator is ideal for solar battery sizing. If your solar system requires a certain amount of watt hours per day and you know your battery bank voltage, you can calculate the required amp hour capacity. For example, if you need 3000Wh daily and use a 24V system, you need at least 125Ah (3000 ÷ 24 = 125). This helps you select the right battery size for your off-grid or backup power needs.
Does the calculator work for both lithium and lead-acid batteries?
Yes, the Wh to Ah conversion formula works for all battery types including lithium-ion, LiFePO4 (lithium iron phosphate), lead-acid, AGM, and gel batteries. The conversion is based on fundamental electrical principles that apply universally. However, remember that usable capacity differs between battery types due to different depth of discharge recommendations. Lithium batteries typically allow 80-100% depth of discharge, while lead-acid batteries should only be discharged 50%.
Why do I need to convert between Wh and Ah?
Different manufacturers specify battery capacity in different units. Some use Wh (energy capacity) while others use Ah (charge capacity). Converting between them allows you to compare batteries fairly across brands, design electrical systems accurately, and ensure your battery bank meets your energy requirements. Additionally, solar charge controllers often work in amps, while inverters are rated in watts, making conversion necessary for system compatibility.
Can I convert Ah to Wh with this tool?
Yes, the calculator supports bidirectional conversion. You can convert Wh to Ah or Ah to Wh by clicking the toggle button at the top of the calculator. Simply enter your values and select the conversion direction. The formula for Ah to Wh is: Wh = Ah × V (multiply amp hours by voltage). For example, a 100Ah battery at 12V contains 1200Wh of energy (100 × 12 = 1200).
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